I've found the input tubes have more of an effect on the sound than the output tube. That being said, try a big bottle 6CA7 as an alternative to the EL34. Bigger sound, should be plug compatible in most circuits.
Differences b/n KT-88 and EL-34 Amps?
I'm one of those SS guys thinking about getting into tubes. Most 300B amps seem to be out of my price range, but there seems to be a plethora of KT-88 and EL-34 amp (power and integrated) choices out there. Is there an intrinsic sound to each? I mostly listen to classic jazz and blues with the occasional pop/rock romp on the weekends. Please help a newbie tubie . . .